1. Field of the Invention
The present invention relates to an information recording medium, and an information recording and reproduction method and an information recording and reproduction apparatus for the information recording medium.
2. Description of the Related Art
As one type of information recording medium having a sector structure, optical discs are known. Since the recording density and capacity of optical discs have recently been improved, it is important to guarantee the reliability of the optical discs. For this purpose, optical disc apparatuses perform adjustment processing for acquiring recording and reproduction conditions to be utilized for recording information to or reproducing information from the optical disc mounted thereon. The recording and reproduction conditions include a recording power condition showing an optimum power of a semiconductor laser for directing light toward an optical disc for recording data. The recording power condition can be acquired by recording power adjustment.
One exemplary method for recording power adjustment is described in Japanese Laid-Open Publication No. 4-141827. Recording power adjustment is performed each time an optical disc apparatus is activated after an optical disc is mounted thereon, or each time the characteristics of the optical disc or the optical disc apparatus are changed by a predetermined level by a factor of a temperature change or the like.
The recording and reproduction conditions including a recording power condition can be acquired in a drive test area in an inner peripheral portion or a drive test area in an outer portion of the optical disc. The optical disc apparatus performs recording and reproduction processing to and from an optical disc mounted thereon using the acquired recording and reproduction conditions.
Due to the recent further improvement in the recording density and capacity of optical discs, there now occurs a case where the recording and reproduction conditions which are acquired in the drive test area in accordance with a conventional method are not appropriate. There is a case where such recording and reproduction conditions are not appropriate to the entire disc, or there is a case where such recording and reproduction conditions are not appropriate when the optical disc apparatus performs recording and reproduction at a different apparatus temperature from the apparatus temperature at which the recording and reproduction conditions were acquired. One conceivable method for adjusting the recording and reproduction conditions is to acquire the recording and reproduction conditions in a drive test area before each recording or reproduction operation is performed. This extends the time period required for adjusting the recording and reproduction conditions, which is impractical.